66397556657 has 2 divisors, whose sum is σ = 66397556658. Its totient is φ = 66397556656.

The previous prime is 66397556573. The next prime is 66397556711. The reversal of 66397556657 is 75665579366.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66277413136 + 120143521 = 257444^2 + 10961^2 .

It is a cyclic number.

It is not a de Polignac number, because 66397556657 - 2¹⁰ = 66397555633 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 66397556593 and 66397556602.

It is not a weakly prime, because it can be changed into another prime (66397556257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33198778328 + 33198778329.

It is an arithmetic number, because the mean of its divisors is an integer number (33198778329).

Almost surely, 2^66397556657 is an apocalyptic number.

It is an amenable number.

66397556657 is a deficient number, since it is larger than the sum of its proper divisors (1).

66397556657 is an equidigital number, since it uses as much as digits as its factorization.

66397556657 is an evil number, because the sum of its binary digits is even.

The product of its digits is 214326000, while the sum is 65.

The spelling of 66397556657 in words is "sixty-six billion, three hundred ninety-seven million, five hundred fifty-six thousand, six hundred fifty-seven".